The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.
Battery packs used with electric vehicles store large amounts of energy in a small space, producing high energy densities. These battery packs include an external housing that is designed for more than just environmental protection and packaging efficiency. The housing also enhances safety and stability, particularly under a range of anticipated abnormal operating conditions.
Due to the high energy densities involved, it is known to provide internal safety mechanisms to help ensure that stored energy is controllably released under a narrow set of circumstances. These safety mechanisms interact with mechanical and electrical interfaces provided by an operational vehicle to enable energy charging and discharging.
There are a wide range of situations where energy maintenance and management of a battery pack is needed, and not all of these include situations where the battery pack is installed in a vehicle or a vehicle known to be 100% operational. Some of these situations include storage, transport, and recycling of a high energy battery pack where the battery pack is not installed in an EV. Other situations include operations on a battery pack that is installed in an EV, but the circumstances indicate that operation of the EV, or a subsystem thereof, may be degraded. Degradation may occur from collisions or acts of nature and could compromise a safety system of the battery pack. Even when the safety system is not actually compromised, the state of the vehicle or its environment or status may indicate that there is a risk that the safety system has been compromised. In those situations, it may not be reasonable to expect that the vehicle may be available to provide the necessary interface and safety structures. Of course, there are also situations where maintenance and management operations are needed with respect to a fully functional EV and battery pack.
Maintenance and management operations include charging and discharging a battery pack safely to desired state of charge (SOC) levels. Depending upon the situation, the desired SOC level could require a discharging or a charging operation. Under some circumstances, it is necessary or desirable to perform the operation without benefit of the battery pack being installed into an EV, nor is it always economical or possible in every case to provide an operational EV into which the candidate battery pack may be installed.
One of the incorporated co-pending patent applications includes a discussion of a charging/discharging tool that advantageously under certain circumstances has access to a high-voltage battery pack through a secondary service connection. Sometimes it is the case that the primary service connection is unavailable while there is significant stranded energy present. These cases may include damage to the primary service connection, internal fault with the energy storage system, and/or damaged or defective internal connections. Sometimes it is the case that use of an external discharger unit is not possible, or the external discharger unit is unavailable.
Even in situations when the primary service connection is available, use of a charging/discharging tool through this connection may add undesired costs and complexities under some scenarios. In order to operate the primary service connection typically used by an electric vehicle, the charging/discharging requires costly CAN communication, special connectors, time to disconnect the vehicle electrical connector and install the connector to the external device, and configuration/use of any simulator to emulate conditions of the operating environment in cases where there are failsafe protections inhibiting direct access by such a tool.
An energy storage system installed in an EV with significant stranded energy may be implicated by first responders (e.g., fire fighters, security, and emergency personnel) and second responders (e.g., tow truck drivers, dismantlers, junk yards, and auto-salvagers). Whether there is a need for rapid response or access by persons who may lack monetary resources, training, or technical background to address the stranded energy through the primary service connection using a specialized and sophisticated charging/discharging tool, it can be problematic when access to the energy storage system is limited.
What is needed is an apparatus and method for providing energy management and maintenance of a high energy battery pack through use self-discharge features.